1. Technical Field
This invention relates generally to devices and methods for monitoring the location of a person, and more particularly to a self-contained audible alarm system, and corresponding method, that detects when a person, such as a patient in a hospital, moves from a position in a bed, wheelchair, or other furnishing.
2. Background Art
There are many situations in which a person is directed not be ambulatory. For example, a person recovering from surgery may be confined to bed rest for a predetermined amount of time. Similarly, a person recovering from a broken leg may be confined to a wheelchair until the leg sufficiently heals. Elderly patients may need the assistance of a nurse before moving on their own. Further, patients that are heavily medicated or sedated may be prone to slippage or falls, and may thus be sequestered to a bed or chair.
It can therefore be problematic when a person who should be confined to a wheelchair or bed tries to get up. They may slip and fall, thereby injuring themselves or exacerbating existing injuries. Additionally, if a patient falls out of a bed or wheelchair, they may render themselves unable to call for help. As there are generally many more patients than staff in a healthcare facility, it is often impossible to watch each patient all the time. A need exists, therefore, for a monitoring system that provides a warning to the caregiver when a patient has exited his chair or bed.
Several manufacturers have attempted to solve this problem. For instance, mechanical restraints can be used to physically confine a person to a bed or wheelchair. The problem with the use of these restraints, in addition to potentially violating patient rights and affecting patient dignity, is that the restraints may cause additional injury by binding the patient. Further, the patient in restraints may not be able to complete simple tasks such as feeding himself or changing the television channel.
Another attempt to solve the problem involves a system using magnetic tab alarms. These alarms feature a bulky control unit that is coupled to a plurality of tabs by way of tether cords. One end of the tether cord attaches to the control unit, while the other attaches to the patient's clothing. An alarm in the control unit sounds when the person moves sufficiently from the control unit as to cause the magnet or tab to dislocate from the control unit. A drawback to these systems is that they often emit false alarms as the tabs can become dislocated from simple actions such as the patient turning over. Additionally, the tether cord can become tangled with the patient's arms and legs. Next, the control unit can easily be dropped on the floor, thereby rendering it inoperable. As the control units are generally quite expensive, breakage by dropping results in significantly increased costs for the healthcare facility.
Another prior art solution involves the use of infrared light to monitor a person's location. When a person moves, infrared sensors attempt to detect this movement, thereby sending a notification signal to a remotely located control unit. The problem with these systems is that they generally must be positioned a good distance away from the patient so as to monitor the patient's full body. As such, a patient may be completely out of the bed or falling to the ground before the alarm sounds. Further, caregivers often falsely trip the infrared beams. The potential also exists for a person to defeat the system by maneuvering in a manner in which to avoid the infrared beam's detection.
There is thus a need for an inexpensive, reliable system for monitoring a person's position in a bed or chair that is reliable, resistant to breakage, not prone to nuisance tripping, and that is not easily circumvented by the person.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.